Ice caves of Irkutsk amphitheatre as objects of natural heritage
E.V. Trofimova
Institute of Geography, Russian Academy of Sciences, Moscow
На примере Иркутского амфитеатра рассматриваются подходы к оценке научной значимости пещер с многолетним льдом — объектов природного наследия.
Geographical peculiarities of the region explored
The region explored is situated at the heart of Asia, near the famous Lake Baikal (Fig. 1), geographical position is 51°08'—64°15' N and 95°38'-119° 10' E, the altitudes vary from 158 to 2999 m a.s.l. Karst rocks occupy some 50 % of Irkutsk amphitheatre, a total more than 400 000 km2. Dissolved rocks are disposed in the all stratigraphic stratums and geostructural elements of two main karst regions: the Siberian Platform and its mountain range. Karst is developed, mainly, in carbonate and sulphate rocks of Lower Cambrian, dolomites and limestones of Ordovician, Silurian and Devonian of Platform
and Precambrian rocks of mountain regions — crystalline marbles, limestones and dolomites. Depending on geological, geomorphological and hydrogeological conditions, karst occurs on the surface of the earth or revealed at the depths of more than one kilometer.
There are more than 300 caves have been discovered in Irkutsk amphitheatre, the longest (cavern Botovs-kaya) being the 16 km in the valley of Lena and the deepest pit (Kurtuiskaya) is the 144 m in the valley of Bolchaya Belaya. The severe climatic conditions of a territory considered (the average annual temperatures change from —0,9 °C in the southern parts to —8,6 °C in the
Fig. 1. Ice caves of Irkutsk amphitheatre
1 — 15 — ice caves: 1 — Botovskaya, 2— Argaracan, 3— Nuganskaya, 4— Bolchaya Baidinskaya, 5— Malaya Baidinskaya, 6— Mechta, 7— Skotomogilnik, 8— lya, 9— Zagadai, 10— Burun, 11— Burun-ledyanaya, 12— Korona, 13— Bolchaya Onotskaya, 14 — Balaganskaya, 15 — Urungaiskaya, 16 — Bolchaya Nizneudinskaya, 17 — Malaya Nizhneudinskaya Рис. 1. Пещеры с многолетним льдом Иркутского амфитеатра
1 — 15— пещеры: 1 — Ботовская, 2 — Аргаракан, 3 — Нуганская, 4— Большая Байдинская, 5— Малая Байдинская, 6— Мечта, 7 — Скотомогильник, 8— Ая, 9— Загадай, 10— Бурун, 11— Бурун-ледяная, 12— Корона, 13— Большая Онотская, 14 — Балаганская, 15 — Урунгайская, 16 — Большая Нижнеудинская, 17 — Малая Нижнеудинская
Ice caves of Irkutsk amphitheatre
Table
Number of cave Name of the cave Length, m Depth, m Volume, m3
1 Botovskaya >16 000 8 15
2 Argaracan >5000 57 95
3 Nuganskaya 5 2 0,5
4 Bolchaya Baidinskaya 45 11 120
5 Malaya Baidinskaya 55 8 8,0
6 Mechta 823 52 70
7 Skotomogilnik 30 8 3,5
8 lya 578 32 3,0
9 Zagadai 600 20 2,5
10 Burun 26 3 3,0
11 Burun-ledyanaya 67 44 4,5
12 Korona 76 12 1,5
13 Bolchaya Onotskaya 226 60 2,5
14 Balaganskaya 300 20 10,0
15 Urungaiskaya 780 28 2000
16 Bolchaya Nizhneudinskaya 500 20 3,5
17 Malaya Nizhneudinskaya 120 12 3,0
northern parts) caused, largely, the wide-spread of the caves with the permanent ice. The most known ones are represented on the Fig.1 and in Table.
Patrimony valuation of ice caves
Three caves — Argaracan, Bolchaya Baidinskaya and Urungaiskaya are the representative ice cavities of Irkutsk amphitheatre. They are discerned by its geographical position — on the plateau, in the mountain and on the shore of Lake Baikal, and are distinguished by the sizes of underground glaciation (see Table). Argaracan (2, here and in the rest of the text the number corresponds to that shown on Fig.1 and in Table), is situated on the Srednesi-birskoe plateau, Bolchaya Baidinskaya (4) was formed on the western shore of Lake Baikal and Urungaiskaya (15) is located in the mountain of Vostochny Sayan. All cavities are the objects of natural heritage, there are the State Natural Monuments and have a scientific, aesthetic and instructive importance.
Cave Argaracan (2) is disposed on the right slope of the stream Argaracan (left tributary of river Lena), on the height of 40 m above the bottom of the stream valley. The cavern was formed in the limestones and dolomites dated by the Lower Cambrian. It is one of the largest caves in the Region. Morphometric characters of the cavity and volumes of the ice accumulations are represented in Table. The cavern was discovered and explored by the geologists G.P. Vologodsky [1] and A.P. Vagina in 1968. Its underground cavern is of complicated multi-level cavity kind. The first level is characterized by wide spread of snow and ice formations (Fig. 2, a), the flowstones are wide developed on the second floor. This cave has two entrances: the first is disposed at the bottom of the karst
pothole (by diameter of 4 m and the depth of 1 m), the second, also situated at the bottom of the small karst pothole, is impassable for the man. According to the origin of the coldness and accumulation of snow and ice in the cavity, Argaracan has been allocated to the thermoventi-lated caves, which is distinguished by the change of direction of air draught in cold and warm seasons. During all the year, the temperatures of the air on the first floor of cavity are negative: its range from —1°, —3 °C in warm seasons to —12°, —14 °C in cold ones.
Deposited and metamorphosed ice is formed near the entrances to the cave every year: there are the small snowbanks. Congelation and sublimated ice have been noted inside of the cavity. First of all, there is a huge aufeis with area approximately 35 m2 (Fig. 2, a). In 2004 the ice core was drilled in the ice body, at the centre of the aufeis. Its depth reached 2.2 m. But as the object of natural heritage Aragaracan is really known thanks to the unique ice crystals observed at the ceilings and on the walls above and near the aufeis. There is sublimated ice in the shape of the plates and needle forms. In spring the sizes of crystals of plates reach to 8—10 cm in diameter, the length of needles exceeds 5 cm. Needle ice crystals thaw usually by July. Ice stalactites and stalagmites have been mentioned in Argara-can. Its forms and sizes are distinguished by considerable variety. Conic, complicated ice stalactites and stalagmites occur here, with the length up to 1.5—2 m.
In spite of existence of a big swamp massif around Argaracan, this popular ice cave is visited actively, usually in winter season — from November to April, by the inhabitants, speleologists and tourists. Last five-six years the important growth of the recreational pressure is marked in this ice cavern.
E.V. Trofimova
Fig. 2. Plans of caves Argaracan (a), Bolchaya Baidinskaya (b) and Urungaiskaya (c) Рис. 2. Топосъемки пещер Аргаракан (a), Большой Байдинской (b) и Урунгайской (с)
Cave Bolchaya Baidinskaya (4) is disposed near the coastal escarp of the western shore of Lake Baikal, at the altitude of 300 m above the lake level. Its characters are represented in Table. The cavity was formed in the meta-morphic complexes from Archaean-Lower Proterozoic consisting of marbles and calciphyres. For the first time it
was researched by P.P. Khorochikh in 1923 [3]. The temperatures in the Hall Khorochikh vary from 0—2 °C in warm season to —5°, —10 °C in cold period.
As it was described in [2, 4], Bolchaya Baidinskaya is the cold cave with a sack-shaped morphology, characterized by descending winter type of air circulation. As it
shown on the Fig. 2, b, the different ice types are noted in this underground cavity: congelation, sublimated, as well as deposited and metamorphosed ice. A permanent snowbank made by snow, firn and ice is located in cavern explored, its depth is 8.2 m, volume is 110 m3. The observations under dynamics of this snow-bank were organized in 1993. During 1993—2005 the rate of ice retreat varied from 10.8 to 12.6 cm per year and the rate of the its thaw achieved 12.9 cm per year.
The ice sample from the snow-bank considered (picked on the height of 1.5 m above the cave floor) was researched at the laboratory. Spores and pollen analysis indicated the presence in the sample the following forest associations in conditions of the recent steppe landscape on the surface (the analysis was accomplished by V.A. Micharina):
Pinus silvestrus 17.5 %
Pinus sibirica 45.0 %
Picea obovata L. 1.5 %
Larix sibirica L. 2.0 %
Abia sibirica L. 2.5 %
Betula verrucosa Ehrh. 4.5 %
Salix captea L. 2.0 %
Compositas 2.5 %
Ephedre 2.5 %
Selaginelle selaginoides 180 %
Sphagnum sp. 1.5 %
Lycopodium annotinum L. 0.5 %
It is obvious that the more deep explorations of this
snow-bank will permit to reconstruct the paleoclimatic conditions on the western shore of Lake Baikal. In consequence of its geographical position the cave Bolchaya Baidinskaya is visited actively during all the year.
Cave Urungaiskaya (15) is located in the mountain Vostochny Sayan in the valley of Uda at the height of 450 m above the bottom of the valley. In the sixtieth of XX century Urungaiskaya was discovered by the local teacher of geography M.I. Pugachev, after, in seventieth, underground cavity was explored by the speleologists of Irkutsk regional speleological club. Underground cavity was formed in marbles dated by Lower Proterozoic. The average temperatures of the air in Hall Kristalny are ranged from 0°,—3 °C in warm season to —6°, —8 °C in cold period.
Urungaiskaya has been allocated to the cold cavern with a sack-shaped morphology. The cave has four etages. The snow and ice formations are observed on the third etage. As it shown on the Fig. 2, c, different types of the ice are mentioned in this underground cavity: congela-
tion, sublimated, as well as the deposited and metamorphosed ice.
The ample aufeis with the permanent ice has the area is exceeding 650 m2, and its thickness varies from 2 up 4—4.5 m. A lot of exotic ice formations, named, for example, «Besedka Snezhnoi korolevi» — «Summer-house of Snow queen»(ice stalagnate), «Blisnetsi» — «The twins» (ice stalagmite), etc., are marked on the walls and ceilings of this underground cavity. That is the reason of ice cave Urungaiskaya is very attracti
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